Psychotic symptoms in bipolar disorder (BP) are common, correlate with greater severity of illness, and represent a familial subtype of BP with possible etiological ties to schizophrenia. The long term goal of this K99/R00 application is to uncover susceptibility genes for this serious form of BP. The candidate is a psychiatrist with post-doctoral research experience in mood disorders and genetic epidemiology, who seeks to develop expertise in next-generation DNA sequencing, high-throughput bioinformatics and statistical methods to help uncover the genetic underpinnings of psychotic BP. The primary hypothesis to be tested is that susceptibility genes for psychotic BP will harbor both common and rare causal variants. To test this hypothesis, we propose the following specific aims: (1) To perform a secondary analysis of a BP genome-wide association study (GWAS) using 1200 psychotic BP cases, 900 non-psychotic BP cases and 1500 controls, and to replicate our best findings in a similarly powered independent replication sample. (2) To select genes that meet genome-wide significance in the combined discovery and replication sample and sequence all exons, UTRs, promoters, and highly conserved sequences in 500 cases with psychotic BP and 500 controls using a novel microarray enrichment technique and second generation high-throughput sequencing technology. (3) To validate our findings by performing: a) case-control replication analysis of 1000 additional cases with psychotic BP and 1000 controls; b) selected sequencing of multiply affected families to find evidence of co-segregation between a putative causal variant and disease status. The training and research proposal will enable the candidate to develop into an independent investigator in psychiatric genetics, and has the potential to identify novel susceptibility variants for psychotic BP. Primary mentorship will be provided by Dr. James Potash, director of research for mood disorders at Johns Hopkins, with co-mentorship from Dr. Richard McCombie, co-director of the CSHL Genome Center and an expert in high throughput sequencing and Dr. Peter Zandi, a genetic epidemiologist with expertise in bioinformatics .